Sorry to make this chain subject awkward, but the manual states that the chain slack (50-60mm) should be measured with the bike on its sidestand, and with no weight on it, ie suspension fully extended.

For what it's worth, I set my adjustment with my bike on its centrestand, which is the same in theory as an unladen bike leaning on its sidestand. The only problem with the sidestand idea is the assumption that the suspension will be fully extended. Depending on the spring rate/preload used, this may not happen if the shock is set up to be soft.

I agonised over the chain slack question after having set it much too tight at one stage. I figure the above explanation is right after I compressed the suspension with two strong tiedowns, and then set the slack so the chain wasn't tight with the three axles/pivots as close to being in line as possible. I then released the tiedowns and measured the slack with the suspension fully extended, and sure enough, it was pretty close to 50mm.

I hope this isn't too long-winded, and makes sense. Why Yamaha didn't fit a rear chain guide I do not know . Bloody penny pinching maybe. Even a DR650 has a decent one.

You are not being awkward, the workshop manual says different to the user manual.......

As long as the tension isn't too great when all the points are in a straight line then you are never going to damage anything. Of course, too much slack and the chain might skip off the rear sprocket. Hmm, I wonder if anyone has made a chain guide that works yet....... Nope can't think of anyone who might have done that

__________________
>-------<

Never underestimate the power of stupid people in large groups.

Ha ha good one mate! Yes, I think I'll have to go that way myself.

The service manual states that chain slack should be 50-60mm when the bike is held upright, both wheels on the ground and no rider on.

The owner's manual says sidestand.

TBH I never bother measuring mine, just check there's still a bit of slack with as much of my weight as I can get right on the back of the bike.

__________________
I spent a lot of money on travel and racing motorcycles - the rest I just squandered.

XT660Z - Commuter, Adventurer...Racer?

www.dashmoto.net

Other bikes >> MT-03 / CG125BR-J / ER-6F
Departed >> ZXR400L3 / EC300 / DR-Z400E / DR800S / GPZ500S / GS400

I know... and there's quite a bit of variation between those... To be honest I have no idea how you could even get a 50-60mm slack with the bike upright since that means the chain would need to go into the swingarm...

Since I had some problems with the first chain on the bike - a ride of about 800km in which i haven't checked it and it jumped off the rear sprocket locking the wheel - I'm trying to figure which is ideal to avoid both wear and incidents.

I think i'll go on too and check what happens if i use some ties to pull the wheel up until front sprocket, swing arm axle and rear sprocket are in the same line, adjust the chain at that point so is not too tight and then see what happens when the bike is in either options Yamaha gives in different manuals.